This section provides background information related to the present disclosure which is not necessarily prior art. The background information provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Motorized vehicles may include a powertrain that includes a powerplant (e.g., an engine, an electric motor, and/or a combination thereof), a multispeed transmission, and a differential or final drive train. The powerplant may include an engine that produces drive torque that is transmitted through one of various gear ratios of the transmission to the final drive train to drive wheels of the vehicle. The engine may produce drive torque by combusting an air-fuel mixture in cylinders of the engine. The air-fuel mixture may be controlled by one or more electronic control modules.
Some system diagnostics are performed on the vehicle while the vehicle is operating. Because the vehicle is operating, the system diagnostics may be intrusive. One type of system diagnostic is a fuel adjustment system diagnostic (FASD). The FASD is effective at diagnosing many fuel delivery, air delivery and some exhaust system malfunctions. Because portions of the FASD test are intrusive, drivability issues caused by air/fuel delivery disturbances, particularly at idle or low speed conditions, are evident to the vehicle operators.